u-blox LEA-5 Series Hardware Manual page 43

Firmware supports an active antenna supervisor circuit, which is connected to the pin AADET_N. An example of
an open circuit detection circuit is shown in Figure 36 and Figure 37. High on AADET_N means that an external
antenna is not connected.
Short Circuit Detection (SCD)
A short circuit in the active antenna pulls V_ANT to ground. This is detected inside the u-blox 5 module and the
antenna supply voltage will be immediately shut down.
Antenna short detection (SCD) and control is enabled by default.
Open Circuit Detection (OCD)
GND
RF_IN
GND
VCC_RF
V_ANT
AADET_N
u-blox 5 Module
Figure 36: Schematic of open circuit detection variant A (for exact pin orientation see data sheet)
References Value
R1
10
R2
560
R3
100 k
u1 LT6000
Table 9: Active antenna supervisor, bill of material
R 2
R 2 R 3
I Vcc
R 1
Equation 1: Calculation of threshold current for open circuit detection
If the antenna supply voltage is not derived from Vcc_RF, do not exceed the maximum voltage rating of
AADET_N.
GPS.G5-MS5-09027-A2
R1
Tolerance
5%
5%
5%
_ RF
LEA-5, NEO-5, TIM-5H - Hardware Integration Manual
R2
u1
R3
Description
Resistor, min 0.063 W
Resistor
Resistor
Rail to Rail Op Amp
Released
Remarks
Design-in
Page 43 of 68